Chilean police have fired water cannon and clashed with high school students who were protesting in the capital, Santiago, over education reforms.
More than 100 were detained after rocks were thrown at police, officials said.
Huge protests in May and June had led the government to meet most of the students' demands, including scrapping a college entrance exam fee.
But the students say they are angry at the slow pace of President Michelle Bachelet's promised reforms.
Education Minister Yasna Provoste said the latest protests were not justified.
Student leaders had called a one-day strike and several hundred students marched on the education ministry on Wednesday.
Police officers blocked their path and arrests were made after some protesters threw rocks and paint bombs at police vehicles.
Deputy Interior Minister Felipe Harboe told Associated Press 114 students were detained.
The protest was far smaller than those in the summer, when up to 700,000 students joined marches.
President Bachelet, who is currently visiting Germany, agreed to scrap the exam fee and set up an advisory panel, including students, to review the education system.
But one of the student leaders, Max Mellado, said on Wednesday the panel was "good for nothing".